On the other hand we have to control its use, so that we can make the best out of it, i.e. use it safely and efficiently, and harness it to achieve qualities like speed, accuracy and efficiency.

Electrical Engineers should understand the path that energy takes from coal, water, or other fuel to robot, heater or computer, and be able–based on this understanding – to specify or design equipment and systems.

In their work related to this material, they will have to use concepts and methods that they learn in courses as diverse as computers, mathematics, electronics and control theory. This course serves only as an introduction to both electrical machines and power electronics.

It focuses on the most common devices and systems that an electrical engineer will encounter: AC machines, transformers, rectifiers and inverters, as well as Electrical Drives and Uninterruptible Power Supplies. A lot is left out, e.g.:

Commutation of DC machines,

Dynamic models of Electrical Machines,

Design of Electrical Machines,

Analytical discussion of PWM inverters and matrix converters…

Control of Electrical Drives

AC machines

Three Phase Windings

Flux linkage plays a crucial role in the operation of both DC and AC machines. In this chapter, the geometry and the operation of windings in AC machines is discussed. The flux varies in time, and can also vary in position, or be stationary.

To understand how these machines operate, the concept of space vectors (or space phasors) is introduced.

Figure 1 – A simple two-pole, single phase synchronous generator, the spatial distribution of the magnetic field relative to the magnetic axis of the armature winding, and the time dependent induced voltage in the armature winding.

Electric machines often have defined an armature winding which is the winding that is power producing, and a field winding that generates the magnetic field. Either could be on the stator or rotor depending on the specific motor or generator.

However it is more common with AC machines such as synchronous or induction machines that the armature winding is on the stator (the stationary portion of the motor). Synchronous machines have field windings on the rotor that is excited by direct current delivered to the rotor windings by slip rings or collector rings by carbon brushes.

The field winding produces the north and south poles, thus the image shown in Figure 1 is for a two-pole, single phase (one armature winding) synchronous generator.

The magnetic axis for the armature winding is perpendicular to the area defined by the armature winding (armature winding is the perimeter of this area).